Echo Provider
The Echo Provider is a simple utility provider that returns the input prompt as the output. It's particularly useful for testing, debugging, and validating pre-generated outputs without making any external API calls.
Configuration
To use the Echo Provider, set the provider ID to echo
in your configuration file:
providers:
- echo
# or
- id: echo
label: pass through provider
Response Format
The Echo Provider returns a complete ProviderResponse
object with the following fields:
output
: The original input stringcost
: Always 0cached
: Always falsetokenUsage
: Set to{ total: 0, prompt: 0, completion: 0 }
isRefusal
: Always falsemetadata
: Any additional metadata provided in the context
Usage
The Echo Provider requires no additional configuration and returns the input after performing any variable substitutions.
Example
providers:
- echo
- openai:chat:gpt-4o-mini
prompts:
- 'Summarize this: {{text}}'
tests:
- vars:
text: 'The quick brown fox jumps over the lazy dog.'
assert:
- type: contains
value: 'quick brown fox'
- type: similar
value: '{{text}}'
threshold: 0.75
In this example, the Echo Provider returns the exact input after variable substitution, while the OpenAI provider generates a summary.
Use Cases and Working with Pre-generated Outputs
The Echo Provider is useful for:
-
Debugging and Testing Prompts: Ensure prompts and variable substitutions work correctly before using complex providers.
-
Assertion and Pre-generated Output Evaluation: Test assertion logic on known inputs and validate pre-generated outputs without new API calls.
-
Testing Transformations: Test how transformations affect the output without the variability of an LLM response.
-
Mocking in Test Environments: Use as a drop-in replacement for other providers in test environments when you don't want to make actual API calls.